Developing agent and method for manufacturing the same

Abstract

It is intended to provide a method includes the step of forming agglomerated particles by agglomerating fine particulate mixture containing a binder resin and a colorant. In the step of forming agglomerated particles, a cationic organic coagulating agent having an average molecular weight of from 1000 to 100000 is added to a liquid dispersion containing fine particles.

1. A production method of a developing agent comprising:
 melt kneading and pulverizing a mixture containing at least a polyester resin and a coloring agent to form a particulate mixture; 
 dispersing the particulate mixture in an aqueous medium to form a liquid dispersion of the particulate mixture, and subjecting the liquid dispersion to mechanical shearing to pulverize the particulate mixture to form fine particles, 
 adding a cationic organic coagulating agent having an average molecular weight of from 1000 to 100000 to a liquid dispersion of the fine particles; and 
 forming agglomerated particles by agglomerating fine particles in the aqueous medium. 
 
     
     
       2. The method according to  claim 1 , wherein the cationic organic coagulating agent is a quaternary ammonium salt. 
     
     
       3. The method according to  claim 1 , further comprising adding a pH adjusting agent when the cationic organic coagulating agent is added. 
     
     
       4. The method according to  claim 1 , further comprising adding a monovalent metal salt when the cationic organic coagulating agent is added. 
     
     
       5. A developing agent containing agglomerated particles which are obtained by melt kneading and pulverizing a mixture containing at least a polyester binder resin and a coloring agent to form a particulate mixture,
 adding a cationic organic coagulating agent having an average molecular weight of from 1000 to 100000 to a liquid dispersion of the fine particles, and 
 forming agglomerated particles by agglomerating fine particles in the aqueous medium. 
 
     
     
       6. The developing agent according to  claim 5 , wherein the cationic organic coagulating agent is a quaternary ammonium salt. 
     
     
       7. The developing agent according to  claim 5 , further comprising a monovalent metal salt.